Sandblasting nozzle and method of producing it



Aug. 25, 1959 J. J. RUTLEDGE 2,900,851

SANDBLASTING NOZYZLE AND METHOD OF PRODUCING IT Filed Aug. 19, 1957INVENTOR JOHN J. RUTILDGE =5QREY SANDBLASTING NOZZLE AND METHOD OFPRODUCING IT .lohn J. Rutledge, Philadelphia, Pa. Application August 19,1957, Serial No. 679,024

1 Claim. (Cl. 7G-101) Sandblasting nozzles are widely used in industryfor directing particles of sand or other abrasive material entrained `ina high pressure air stream against surfaces, usually metallic, to cleanand to a certain extent smooth them, the nozzles commercially obtainablecomprising a hollow cylinder adapted for connection at one end to a hosecarrying the air-sand stream and having a small axial port at the otherthrough which the stream is ejected; they are customarily made of castiron and mild steel and lined with an abrasion-resistant material. Thesenozzles are of a diameter which precludes their introduction into narrowspaces such as those between the blades of` a turbine, while because oftheir cylindrical form they are not well adapted for directing theairsand stream around corners so that for both of these reasons theirconvenient employment under numerous conditions is restricted ornegatived. Hence they are useful only for directing the stream againstsurfaces in direct view and cannot be used for Sandblasting surfacesbehind obstructions or otherwise out of line-of-sight.

l It is therefore an object of the present invention to provide animproved Sandblasting nozzle, as well as a method of making it, not opento these objections in that it may be so constructed as readily to beentered in narrow spaces, or to direct the air-sand stream at an angleto its general direction of travel so as to facilitate its,` projectionaround corners and behind obstacles while in certain of its embodimentsthe nozzle may be formed so as to project a plurality of divergentstreams or a flat one having divergent side edges.

Further objects are the provision of an improved sandblasting nozzlewhich readily can be produced at low costin accordance with the methodof the invention in the usual machine shop.

Other objects and novel features of design, construction landarrangement of the nozzle itself as well as in the `method of making itare hereinafter more fully set forth or will be apparent from thefollowing description of iive different embodiments of the nozzle asillustrated in the accompanyingk drawing, the various figures of UnitedStates Patent O which are intended not only to facilitate description ofi ldesignedto project an air-sand stream at an angle to its generaldirection of flow with a single auxiliary view showing one step in itsmethod of production;

Fig. 4 is a generally similar View illustrating a nozzle "ice adapted todischarge angularly divergent streams with two `auxiliary views showingsteps in its production;

Fig. 5 comprises a perspective view of a nozzle adapted to discharge asingle flattened butv divergent stream with two auxiliary views showingsteps in it production, and

Fig. 6 is a longitudinal section illustrating a nozzle constructed inaccordance with the invention adapted to discharge a stream at lan anglegreater than from the general direction of axial flow.

As the initial step in the production of all the aforesaid nozzles amild steel tube or pipe 1 of desired length and preferably relativelyheavy wall having an axial bore 2 of suitable diameter, for example 1A",and usually externally threaded as at 3 adjacent its rear end tofacilitate coupling to the hose with which the nozzle is to beassociated, is rst .reduced in diameter by turning or otherwise at itsopposite end 4 to leave a wall of about JAG" thickness, for anappropriate distance such as 1%" from the extermity of the tube andterminating at a shoulder 5; the tube then appears substantially asshown in Fig. l.

In producing a nozzle such as shown in Fig. 2l the tube is then clampedby any appropriate means so as to hold l it steady and a preferablycylindrical element such as a rod 6 of carbon, although other materialsmay be utilized as hereinafter noted, is inserted in the borerof thereduced end 4 to extend therein for a relatively considerable distance,preferably at least one-half the length of the reduced portion, the rodbeing of a diameter to form a fairly snug t inthe tube bore so that nomaterial clearance is left between it and the wall thereof; no clearanceis vtherefore indicated in the drawing although it is not essential thatthe element be a tight tit in the bore. The parts then appear as at a(Fig. 2).4

The reduced end of the tube is next heated with a Welding torch or otherappropriate means until it reaches a temperature just below that atwhich it becomes appreciably soft and tungsten carbide or other highlyabrasion-resistant material is then built up progressively about saidreduced end Aas well as `about that portion of element 6 closelyadjacent its extrem-ity and preferably for a short distance about thebody ofthe tube rearwardly of shoulder 5 until the maximum outsidediameter of the generally cylindrical body of tungsten 1 carbide 7 isslightly greater than that of the body ofthe tube, all substantially" asshown at b. After completion of the building-up step just described,which is of course performed by ordinary welding procedure and with' asuitable welding rod, the carbon element 6 is Withdrawn after the partshave become sufliciently cool, an operation whichreadily can beperformed since tungstencarbide does not adhere to carbon, and to impart:an appropriate finish the extremity 9 of the built-up portion finallyforming the nozzle tip may be faced off normal to the axis of the bore,thus completing the production of thenozzle as shown at c. Of course ifdesired the relatively rough and irregular periphery of the built-upportion may` likewise be ground to coincidence with the exterior of thetube audunder some circumstances the end facing 'be omitted sinceneither operation materially `enhances the utility of` the nozzleaiidboth increase its cost of production, particularly since the.tungsten carbide is so hard it is extremely detrimental to grindingwheels.` f While various tungsten carbide alloys`, if they may besotermed, or other material susceptible by progressive deposition underheat of being formed into an extremely hard abrasion-resistant mass canbe utilized in the production of the nozzle, I prefer to `employ `aweldingrod 'of the character disclosed in U.S. Patent 1,803,875

marketed by the Stoody Company, Whittier, California,y

vto "expand under heat and so freeze within the tube,

thus rendering their removal therefrom more difficult .than that of `acarbon element.

Mention has been made of the heating of the reduced ,end of the tubeclose to its melting point before application of the tungsten carbidethereto, such heating enabling the latter to penetrate and alloy with.the thinsteel wall and enhance its subsequent resistance to abrasion,but care must be taken that this heating be not sufiicient to inducecollapse ofthe wall either before or during the building-up of thetungsten carbide about it which, should it occur, would restrict or evenclose the bore inwardly of the element.

A nozzle produced in the manner just described may be used inSandblasting operations and the like in a manner similar to that of thecustomary commercial nozz les presently available in the market. Sinceit can be constructed to present a relatively small external Adiameterit can be introduced into spacestoo narrow to enable entry of ordinarycommercial nozzles, a matter of great advantage in numerous industrialoperations such, for example, as the cleaning of turbine blades asheretofore ymentioned, Moreover, since the length of the tube employedin the production of the nozzle is a matter of choice one up to severalfeet in length may be utilized Iif desired which frequently facilitatesapplication of the `Asandblast at a point remote from an operative.

In Fig. 3 is shown another embodiment of my nozzle which is capable ofdirecting the air-sandV stream at an angle to the main bore and, asshown at d, in the production of a nozzle of this character the element6 instead of being entered axially in the bore after the end of the tubehas been reduced in diameter as already described vis inserted thereinat an angle to the axis of the latter and maintained in that position byIany appropriate means while the tungsten carbide 7 is being built upabout the reduced end of the tube and the element, with the result Athatafter extraction of the latter the nozzle presents the appearance shownat e in which its extremity is illus- -trated as faced off at 9 in aplane normal to the axis vof the angular portion of its bore.

Such a nozzle is often of great utility in directing the air-sand blastinto out-of-the-way places, around corners `and behind interveningobjects, and it will of course be appreciated that the angular diversionof the stream with respect to the axis of the bore of the tube iscontrolled by the angular disposition of element 6 preparatory tobuilding-up the tungsten carbide about the reduced end of the tube Vandabout the element. Hence by varying this angularity the nozzle may beformed to project the stream at lany desired angularity within arelatively considerable arc with respect to said axis to thereby adaptit for a particular service. If the angularity desired is at 90 degreesor more from the direction of axial flow, a transversc bore is made inone side of the reduced portion of the tube close to the outer end andthe element 6 is inserted in thsbore at thedesired angle. The end isthen built up with tungsten carbide as previouslyldescribed and finallythe lelement is removed and the nozzle trimmed. Such ,nozzles typied inFig. 6 are particularly useful in Sandblasting diicultly accessiblesurfaces facing away Afrom the operator such as the inward surfaces ofturbine shroud rings.

The embodiment shown in Fig. 4 is effective to divide the main air-sandstream and project it in two divergent ones as will be apparent from aninspection of the axial section of the finished nozzle shown at h. Inits production, after appropriate reduction of end 4 of tube 1, adiametrically extending slot l10 is cut in its extremity and two carbonor other elements 6, 6 then inserted in this slot at their innerextremities in the manner generally shown at g preparatory to thereafterbuilding up the tungsten carbide 7 about both of them and the reducedend of the tube substantially as already described, with the result thatafter removal of the elements divergent passages l1 extend from the mainbore to the tip of the nozzle which of course may be faced off adjacentthe mouths of the passages either normal to their respective axes orotherwise. In operation, therefore, two separate divergent air-sandstreams are projected from the passages to impinge at separated pointson the article being sandblasted.

Finally in Fig. 5 there is shown in fragmentary perspective Astillanother embodiment of my nozzle which is operative to project a flaring`air-sand stream relatively thin in transverse dimension in comparisonwith its width. In the production of this nozzle, :shown at k, there isinserted in the bore yof the reduced end' of the tube an element 12 ofcarbon or other suitable material having a preferably cylindrical stem13 of diameter appropriate to fit fairly snugly in the bore and lanoutwardly oppositely flared relatively thin portion 14, as-

shown at z' and j, with the result that after the tungsten carbide isbuiltup about said reduced end Fand the flared portion 14 `of theelement so 'as to fully enclose both of its faces and side edges and theelement then removed, a cavity of the general shape indicatedV at l5conforming to the shape of said flared portion is left in the extremityof the nozzle and -is effective to corre spondingly fiatten and divergethe air-sand stream as it passes therefrom. Nozzles adapted -todischarge such streams are desirable for certain classes of work aswhere ylarge 'areas are to be blasted in a of time. After 4 to 8 hoursyof use, the orifices lof the nozzle come eroded to `a funnel shape,which causes undesirable spreading of the stream of sand. This conditionis readily remedied and the nozzle rebuilt Vsubstantially like new byinserting element 6, reheating the nozzle to a ternperature at which thematrix of the abrasion-resistant material lbecomes sufficiently pliable,reshaping the tip to conform tightly about the element, and finallydriving out the latter. lIf desired, instead of merely reshaping thematerial of the tip, mo-re tungsten carbide may be added. This wearingaway and rebuilding of the nozzle may be continued indefinitely. i

Should the tube 1 become perforated by the stream of sand, the damagedpart can be cut out and the Vtip or nozzle welded tothe intact portionof the tubeorto a new tube of any desired length. v

The several nozzles heretofore described arev but exemplary of manytypes which may be constructed by the method of my invention either forgeneral 'sandblasting operations or for particular service under unusualconditions, and in consequence l `d o not thereby desire to restrictmyself specifically to the said embodiments or exactly to the manner oftheir production herein de scribed, las various `changes andmodifications canbe made in the nozzles themselves and in theperformance of the method comprehended by the invention witglioutdeparting from the spirit and scope `of thelatter "as diefined by theappended claim. t

Having` thus described my invention, VI claim ,and desire to protect `byLetters Patent of the United States:V

The method of lmaking a compositesandblasting nozzle which comprises thesteps of reducing'the extremity of a ferrous tube to a diameter lessV,than that ,of its body, inserting in the bore `ofthe lreduced .portion`an element approximating said bore indiameteraud of length sufficientto project. beyond the end face of 4the lreduced 5 6 portion,progressively depositing a matrix of hot sub-f References Cited in thefile of this patent stantialily uid ferrous material containingparticles of UNITED STATES PATENTS tungsten carbide labout and in weldedrelation -to said 2 8 M I l 23 1935 reduced portion, said face vand theprojecting part of the (1)?722; Bm Nga?, 17 1938 element adJacentthereto and, after the material has 5 21324:48 Welch july 20: 1943cooled, removing the element.

